It is the overall objective of this project to develop a Teleost fry explant procedure as a simple, sensitive, rapid method of evaluating aquatic pollutants. Phase I will determine the feasibility of such a system by evaluating the technique with a direct acting procarcinogen (benzidine hydrochloride) and a mutagen (Mitomycin C.) Phase I experiments will utilize two teleost systems -- the sheephead minnow (Cyprinodon variegatus) and the rainbow trout (Salmo gairdneri). Exposed explants will be examined morphologically, cytogenetically (i.e. chromosome banding, sister-chromatid exchange) and evaluated for their ability to form colonies. In addition, the mixed function oxidized system of the explants will be evaluated. In Phase II, it is our intent to produce monoclonal antibodies recognized all surface antigens of transferred cells, and to use these antibodies as reagents as early indications of cell transformations in the teleost explant system.